Even more important than what to get for a pc is how to avoid getting all that extra crap!
To address the question, however, I think a lot of what I'd use has been covered in previous RD epi's.
So aside from the firefoxes, openoffices, and anti-viri, when I set up a new computer for luddite friends I try not to forget:
1. IM Client- GAIM or Trillian
2. Adobe Acrobat
4. iTunes- I make everyone listen to BOL. Also, upgrade WMP
5. Google Picasa- or some other photosharing software
6. RSS Reader- I dunno, Thunderbird...
Also, don't forget to:
7. Change default search to Google
There's better ways to do some of the above things (ie google reader for RSS or flickr for photos), but in my experience, n00bs like icons way better than web favorites with logins.
This is one of those topics where we could use questions and recommendations.
What kinds of software do you want recommendations for, and then what kinds of software do you find essential?